Engine starter gearing



Aug. 12, 1941.

-r. B. MARTIN Y ENGINE STARTER GEARINGr Filed Oct. 18, 1940 3 Sheets-Sheet l 1 INVENTOR. A

' ATTORNEY.

Aug. 12, 1941.

T. B. MARTIN ENGINE STRTER GEARING 3 Sheets-Sheet 2 Y Filed Oct. 18, 1940 W w 9 .Z 5 m M Mw a W W M 5mm.. M m m m k N INVENTOR. vwfnas. mar/iw BY ATTORNEY.

Aug. 12, 1941. T, B MARTlN 2,252,328

l ENGINE STARTER GEARING Filed oct. lss,V 1940 s sheets-sheet 3 i l l INVENTOR. U11/was: BYLT/wmas//Tlar/n/ Patented Aug. 12, 1941 UNITED STATES PATENT OFFICE 2,252,328 n ENGINE STRTER-GEARING Thomas B. Martin, Dayton, Ohio, assignor to Bendix Aviation CorporatillJfSOilthBengLInd., acorporation of Delaware v n ,Application october v18, 1940,*seria1No. 361,755

.torn-J1) 16 Claims.

The present invention relates to engine starter gearing and more particularly toa drive for automatically connecting and disconnecting a starting motor with -a member` of the engine to be started.

It is an object-.of therpresent invention to pro- Vide a `novel engine starterv drive which is effective in operation, `economical vin construction .and small in size asV compared to standard drives `of like capacity.

`It is another object to provide such a device embodying a compressible. cushioning .element with a threaded connection for applying pressure thereto, and a separate threaded connectionfor traversing a pinion into and. out of engagement with a `member of the engine to bestarted.

Furtherobjects and advantages will be apparent from the following description'taken in connection with the accompanying drawings in which:

Fig. 1 is a side elevation partlyin section of a starter drive embodying a `preferred form ofthe invention;

Fig. 2 is a similar viewof a driveof Ithesame type as Fig. .1, adapted for outboard installation;

Fig. 3 isa section taken substantiallyfon-the lined- 3 of Fig. 2; y

Fig.. 4 is .a side elevation partly in section .of another embodiment ,of theinvention; A v

Fig. Y5 isa view similar to Fig. ..4 .showing th parts in driving position;

Fig. 6 isa side .elevation partly in section `.of an.. other form of .the invention;

Fig. '7 is a side view partlylin section of a fur.- ther embodiment of the invention;

yFigli is an end View from .the right :of the structure shown in Fig. '7;

Fig. 9 is a View similar to Fig. 7 showing the parts in driving position;

Fig. 10 is a section taken substantially Aon the line Iii-lil .of Fig. 7 and i 1 Fig. ll `is a detail in perspective of `the pinion and threaded operating members therefor, asillfustrated in Figs. 7 to 10, shown in disassembled relation and partly broken away for the sake of clarity.

In Fig. l of the drawings there is illustrated a power shaft lwhich may be theextended armature shaft of a starting motor, not illustrated. Shaft l is provided with a smooth reduced portion 2 forming a shoulder 3. A plurality of spline grooves 4 are formed in the power shaft beyondv the smooth portion 2, and a further reduced smooth portion 5 is yprovided "beyond the splined portion, the surface of the portion being flush with `the bottoms of the spline grooves, leaving shoulders 5 lat lthe end of :the splined portion.

A pinion l is slidably journalied on the first smooth portion r2 .of the power shaft for longie tudinal movementinto and out of engagement with amember such as a flywheel gear 8' of an engine to be started. YA screw shaft 9 is slidably but non-rotatably mountedon the splined portion 4 of 'theishaft and is provided with a coune terbore Il in which an abutment ring I2 is fix-v edly mounted` in any suitable way .as by welding or` brazing. ,Ring I2 has a sliding fit on the reduced smooth portion 5` of the power shaft and abutsagainst .the shoulders. B on the power shaft to `denne the Vnormal position of the vscrew shaft. A spring I3 bears at :one end against the ring I2 andgatqits otherend against a thimble i4 which partially4 encloses and. retains a cross pin l5 located adjacent the end of the power shaft.

A barrel Vmember l is rigidly fixed in any suitable man-ner as indicated at l1 to 'the pinion 1 in telescopingy relation with the screw shaft` 9 and is provided 4at its free end with a radial flange L8. A; mil? i9, is threaded on the screw shaft i9 4with ,a comparatively low pitch Aand is movable therealong into engagement 'with an abutmentfin the form of `a shoulder 2l which denes the `operative position of the nut. Means fornnormallylretaining the nut in idle position asillustrated, is provided in the form of an anti.- drift spring 22 bearing against a flange 23cm the ASDP :Shoulder 2| of the `screw shaft, and against aeat 2.4 onthe nut'ls.

, Lvathrust connection is provided between the nntland pinion inthe form `of a thrust ring 25 located between the nut andthe lfree end of the barrel 16J .A yielding Adriving connection is provided between the` nut L9 and the pinion barrel .16 comprisinga sleeve 2.6 having a .threaded connect-ionswith .the exterior of the nut 19, which thread -is `,of comparatively high pitch and of opposite hand` to the screw shaft. An .outer barrel member 21 `is fixed to the sleeve26 as by means of lugs 28 of the sleeveextending into slots 29 of the barrel, and retained therein by means of a split lock ring 31. The outer barrel 21 -isprovided with aninwardly extending flange 32, and a ring 33 `of elastieally deformable material is l0- eated between the pinion barrel and outer barrel and between the flange VI8 of `the pinion barrel andiiange -32 of the outerbarrel. As hereshown, flange I 8 isprovided with lugs 34 extending into theslots ZSoft-he outer ibarrel so as t0 spline the pinion barrel to the outer barrel whereby the ring "33 of `fela-stically deformable material is subtween the screw shaft and pinion. Means for.

confining the nut within the sleeve 26 is pro'- vided in the form of a split lock ring 31 located f in the end of the sleeve.

scufng by the telescoping action of the inner and outer barrels during the operation of the drive. l v

In operation, starting with the parts in the positions illustrated, actuation of the power shaft I causes rotation ofscrew shaft v9 whereby the nut I9threads itself along the screw shaft into engagement with the abutment shoulder 2| thereon;n `This -longitudinal motion of the nut is transmitted through the thrust ring to the pinion barrel I'B which moves the pinion into operative position in abutting relation with the shoulder 3 on the power shaft. The pinion 1 engages the shoulder 3 just prior. to the engagement ofthe nut with the abutment 2| on the screw shaft, whereby the screw shaft is caused to.V move backward, against thepressure of the spring I3 until the shoulder 2| engages the nut I9. y.The nutV is thus. effectively locked to the screwV shaft whereby further rotation of the power. shaft 2 causes the nut to rotate in the sleeve 26 whereby saidsleeve is caused to move backward or to the right in Fig. 1 since it is threaded in the opposite direction to the threads of the screw shaft. The backward movement of the sleeve 426 .is transmitted by the lock ring 3| to the outerbarrel 21 which thereupon `compresses the ring 33 between the flange 32 of the outer barrel and the ange I8 of the pinion barrel. When suilicient torque has been built up by the resistance to compression of the member 33, the pinion 1 will be caused to rotate with-the power shaft and crank the'engine. When the lengine starts, the acceleration of the pinion 1 causes the partsto be returned to their idle positions as illustrated. l

In case during the meshing operation a tooth of the pinion 1 should abut against a tooth of the engine gear 8 so as to obstruct the longitudinalv movement of the pinion, the screw shaft 9 will be caused to move backward, compressing the mesh-enforcing spring I3 until sufficient torque has been built up in the threaded connection between the screw shaft and nut to cause the` pinion to be indexed into proper meshing position. When this takes place, the spring I3 expands and snaps the pinion into initial mesh with the engine gear, whereupon meshing and driving take place as usual.

In Figs. 2 and 3 of the drawings, there is illustrated an embodiment of the invention substantially similar to that illustrated, but adapted to an outboard installation in which the pinion moves away from the starting motor rather than toward the starting motor during the meshing operation. As there illustrated, the power shaft 4I has a reduced portion 42 providing a shoul der 43, spline grooves 44 and a furtherV reduced smooth portion 45 flush with the bottoms of the spline grooves., A bearing sleeve 46 is mounted A thimble 38 is preferably provided to protect the ring .33 from.

. toms ,of the splines.

on the smooth portion 45 of the shaft and is retained on the shaft by a thrust collar 41 which bears against and partially encloses a cross pin 48 traversing the free end of the power shaft. A pinion 49 is slidably journalled on the sleeve 46. A screw shaft 5I is slidably but nonrotatably mounted on the splined portion 44 of thepower shaft and is normally held in abutting relation with the sleeve 46 by means of a spring 52 bearing at one end against a Washer 53 seated against the shoulder 43 of the power shaft, and at its other end against a thimble 54 slidably mounted on the power shaft adjacent the end of the screw shaft 5I. The remaining `parts `of this embodiment of the invention are the same as those in Fig. 1 and are similarly numbered'so that further description there- -of is deemed unnecessary.

In the embodiment of the invention illustrated in Figs. 4 and 5, the arrangement of the parts is substantially similar to that illustrated in Fig. 1 except that in this case the screw shaft 6I hasA its stop collar 62 welded or brazed thereon, and-a bushing 63 is welded or brazed in the end of the screw shaft and is provided with slots 64 through which the cross pin 65 extends. The mesh-enforcing spring 66 bears in this instance directly on the end of the screw shaft. The flange 61 is here shown as welded or brazed to the pinion barrel 68, the end of which pinion barrel bears directly against the internally and externally threaded nut 69. In this case, the radial flange 61 of the pinion barrel is not splined to the 'outer barrel 1I whereby the ring of elastically deformable material 12 forms the sole driving connection between the pinion 13 and the outer threaded sleeve 14 so that the ring 12 is subjected to both compression and torsion. The remaining parts of this drive and the operation thereof are the same as previously described with the exceptions noted.

In Fig. 6 of the drawings there i5 illustrated a power shaft 8| having a splined portion 82 and a reduced smooth portion 83 ush with the bot- A pinion -84 is slidably journalled on the shaft 8| for longitudinal movement into and out of engagement with an engine gear 35. A screw shaft 86 is non-rotatably mounted on the splined portion 82 of the power shaft and is prevented from longitudinal movement by means of a cylindrical member 81 fixed in a counterbore of the screw shaft as by welding or brazing and rigidly connected to the power shaft by means of a cross pin 88 retained by a lock ring 89.

An internally and externally threaded nut 9| is mounted on the screw shaft, the internal thread 4being of comparatively low pitch and the external thread of high pitch and opposite hand. A` sleeve member 92 is threaded on the nut 9| and is rigidly connected to an outer barrel member 93 as by means of radial lugs 94 extending into slots 95 of the outerA barrel. A ring I 02 of elastically deformable material is mounted between the inner and outer barrels and between the flange 99 of the pinion barrel and an inwardly extending flange |03 of the outer barrel. A thrust plate member |04 is splined in the outerk barrel 93 as by means of radial lugs |05 slidably mounted in the slots 95 of the barrel, and-a yielding thrust connection from the plate |04. to the pinion barrel 91 is provided in the form of a ring |06 of elastically deformable material interposed between the plate |04 and the flange 99 vof the pinion barrel. Plate |04 is provided .with av central opening-H11 loosely sur-'- rounding the screw shaft 86 whereby the nutifl` is .adapted to engagewtheplateuand move it 1ongitudina11y,1which motion is transmitted through. the elastic :thrust ring |Bft0 the lpinion barrelinlidle position,...al re-entry spring I rinsures en-` gagement ofthe threads of the nut with those of the screw shaft, andfa split ring ||2 retains the nutin` the sleeve 92. 4 f

In Vthe operation of `this embodimentof theinvention, rotation ofthepower shaft 8| is transmitted through the splines.82 to the screw shaft 86 whereby the nut 0| .threads itself along the screw shaft, moving the pinion 84 into engagement with the enginegear 85. When the thrust plate|04 engagesthe shoulder |08 on .thenscrew shaft, further movement of the nut is prevented, whereupon the sleeve92 is caused to move backward, drawing the outer barrel 93 with it and thereby compressing the elastic ring |02 until sufcient .torque is built up to cause rotation of the engine member. If, during the meshing operation, tooth abutment should occur between the' pinion and .engine gear so as to stop the longitudinal movement ofthe pinion, theV elastic ring |06 vis adapted .to Acompress to allow time for friction tol buildup in the threads of the screw shaft and nut to cause indexing of the pinion, whereupon the ring |06 expands to secure initialmesh ofthe pinion, after which meshing and driving take place in the usual manner.

In this embodiment of the invention, the length `of the nut 9|, the slots 85 in the outer barrel and the dimensions of the elastic ring |02 are such that if the drive is subjected vtoa predetermined overload, the sleeve 92 may screw off the end of the nut 9|, thus permitting the nutto overrun. The maximum torque transmitted by the drive is thereby limited to a predetermined value.

In the embodiment of the invention illustrated in Figs. 'l to 11, a power shaft ||5 is-provided with a-spline portion ||6 and a smooth reduced portion ||1 A pinion ||8 is slidably journalled on the power shaft in position to engage Iand drive anengine gear H8. LA' screw shaft- |2| `is non-rotatably mounted'. on the splined ,portion ||6 of the power, shaft .and :is prevented Yfrom longitudinal movement `by. a cylindrical member |22 mounted in a counterbore of the screw shaft and fixed to the powershaft by a crossv pin |23; Pin |23 is retained `by a ring |24 which is locked on the cylindricalmember v|22 by a split ring |25.

An internallyand externally threaded nut '|26 is threaded on'thescrew shaftlwith a low pitch thread, and a sleeve |21, is threaded on the nut with a high pitch thread of opposite hand. An outer barrel member |28 is yfixed to the sleeve |21 as by means of lugs |28 of the sleeve .extending Vinto slots |3| of the barrel member and retained by a split lock ring |32. An inner barrel member |33 is fixed tothe pinion. I8 and has a radial flange |34 provided with lugs" |35 slidably mounted in slots |3| of the outer barrel so as to spline the pinion barrel to the outer barrel. `A ring |30 of elastically deformable material is mounted between the vpinion barrel vand outer barrel fand between the a'nge |34 of the pinion barrel :and .a terminal flange |31 onthe outer barrel. A yielding thrust connection f between the nut |26 and the pinion barrel|33 is provided in the form of a vthrust plate |38 and a yielding ring of elastically deformable material |39 interposed therebetween. Screw shaft |2| is provided with a stop shoulder |4| adapted to be engaged by the nut |26 to dene its operative position and thereby define the meshing position of the pinion I8.

An anti-drift spring |42 is provided for normally retaining the parts in idle position, and a re-entry spring |43 between the screw shaft and pinion insures engagement of the nut A|26 with-the threadsiof the screw shaft upon rotation of the power shaft.

In the operation of this embodiment vof the invention, rotation of the power shaft ||5 and screw shaft |2| causes the nut |26 to be traversed to the left in Fig. 7 until it engages the shoulder |4| `on the screw shaft as illustrated in Fig. 9. Further `rotationof the power shaft causes the sleeve |21 to `be threaded back on the nut, thus compressingthe ring |36 of elastically deformable material `between the flange |34 of the pinion barrelfand ange |31 of the outer barrel untilsuflicient torque Ahas `been builtupto crank the engine. In case of tooth abutment between the pinion and engine gear, the yielding lthrust member |38 ycompresses to provide time for friction to build lup in the threaded connection to index the pinion into proper position, `where-- upon the ring expands to secure initial mesh and the .cranking operation is resumed. In case of overload, the sleeve |21 may move backward sufficiently to run off the `threads of the nut |26 so as to permit the Vnut to rotate, thereby limiting the -maximum torque transmitted by the drive. 1

Although certain embodiments lof the invention have been shown and `described in detail, it will be understood Vthat other embodiments are possible and `various changes may be made in the design and arrangement of the parts without departing from the spirit of the'invention as defined in theclaims appended hereto.

What isclaimed is:

l. In an engine starter-drive, a power shaft, a screw shaft mounted thereon for rotation there with, an internally and externally threaded nut on the screw shaft, a pinion slidab-ly journalled on the powershaft,Y a sleeve threaded on the nut, means transmitting longitudinal movement of the -nut to the pinion in a direction to mesh the piniongwith a member of an engine to be started, and means including a yielding member resisting longitudinal movement of the sleeve away from the pinion and transmitting rotation of the sleeve tothe pinion.

2. In an engine starter drive, a power shaft, a screw shaft mounted thereon for rotation therewith, lan internally and externally threaded nut on theI screw shaft, aV pinion slidably journalled on the power shaft, means including a barrel fixed to the pinion transmitting longitudinal movement of the nut to the pinion, a sleeve threaded on the nut, an outer barrel connected for rotation and longitudinal movement with the sleeve, and means including an elastically compressible member between said barrels resisting longitudinal movement of the sleeve away from the pinion barrel and transmitting rotation of the sleeve 'to the pinion barrel.

3. In an engine starter drive, a power' shaft, a screw shaft mounted thereon for rotation therewith, an internally and `externally threaded nut on the screw shaft, a pinion slidably `journalled on' the powerlshaft,fmeans' including a barrel flxed to the V.pinion ,transmitting longitudinal movement of the nut to the pinion, said screw shaft having an abutment limiting longitudinal movement of thenut thereon in a direction to mesh the pinion with a member of an engine to be started, a sleeve threaded on the nut, and means including an elastically compressible member resisting longitudinal movement of the sleeve away from the pinion barrel and transmitting rotation of the sleeve to the pinion barrel.

4. In an engine starter drive, a power shaft, a screw shaft mounted thereon for rotation therewith, a pinion slidably journalled on the power shaft, a barrel fixed to the pinion having a radially. extending flange, an internally and externally threaded nut on the screw shaft, means transmitting longitudinal movement of the nut to the barrel in adirection to mesh the pinion with a member. of an engine to be started, an outer barrel i surrounding the pinion barrel having an inwardly extending flange, a ring of elastically deformable material surrounding the pinion barrel within the outer barrel between said flanges, and a sleeve non-rotatably connected to the outer barrel threaded on said nut.

5. In an engine starter drive, a power shaft, a screw shaft mounted thereon for rotation therewith, a pinion slidably journalled on the power shaft, a barrel fixed to the pinion having a radially extending flange, an internally and externally threaded nut on the screw shaft, said threads being of opposite hand, an outer barrel surrounding the pinion barrel, a ring of elastically deformable material between said barrels, means transmitting longitudinal movement of the nut to the pinion barrel, a sleeve threaded on the nut, and means transmitting longitudinal movement of the sleeve to the outer barrel.

6. In an engine starter drive, a power shaft, a screw shaft non-rotatably mounted thereon, a pinion slidably journalled on the power shaft for movement into and out of eng-agement with a member of an engine to be started, a nut threaded on the screw shaft, said screw shaft having an abutment defining the operative position of the nut, a barrel fixed to the pinion telescoped over the screw shaft and connected for longitudinal movement with the nut, a ring of elastically deformable material surrounding the pinion barrel, an outer barrel surrounding said ring, and means for yieldingly transmitting rotation from the nut to the pinion barrel including a sleeve threaded on the nut and rigidly connected to the outer barrel.

7. An engine starter drive as set forth in claim 6 in which the length of the threads on the nut and sleeve, and the compressibility of the ring of elastically deformable material are such that the sleeve may run off the threads of the nut and permit the nut to overrun in case of an overload on the drive.

8. In an engine starter drive, a power shaft, a shaft splined thereon having an external thread of comparatively low pitch, an abutment defining the operative position of the screw shaft, means yieldingly holding the screw shaft against said abutment, a pinion slidably journalled on the power shaft, a barrel xed to the pinion, an internally and externally threaded nut on the screw shaft, means transmitting longitudinal movement of the nut to the pinion, a sleeve threaded on the nut with a comparatively high pitch of opposite hand to the screw shaft, and yielding means resisting longitudinal movement of the sleeve and transmitting torque' therefrom to the pinion barrel.

9. In an engine starter drive, a power shaft,

a screw shaft splined thereon having an external thread of comparatively low pitch, an abutment defining the normal position of the screw shaft, means yieldingly holding the screw shaft against said abutment, a pinion slidably journalled on the powershaft, a barrel fixed to the pinion having an outwardly extending flange, an internally and externally threaded nut on the screw shaft, means for transmitting longitudinal movement of the nut to the pinion, a sleeve threaded on the nut with a comparatively high pitch of opposite hand to the screw shaft, an outer barrel member fixed to the sleeve having an inwardly extending flange, and a ring of elastically deformable material between the barrel members adapted to be compressed between said flanges to form a yielding driving connection for the pinion.

' l0. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft having a barrel fixed thereto, a nut threaded on the screw shaft, a yielding thrust connection between the nut and the barrel including a thrust ring of elastically deformable material, a sleeve having a threaded connection with the nut of opposite hand to the screw shaft, and a yielding driving connection between the sleeve and pinion barrel including a ring of elastically deformable material compressed by longitudinal movement of the sleeve. 11. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft having a barrel fixed thereto, a nut threaded on the screw shaft, a yielding thrust connection between the nut and the barrel including a thrust ring of elastically deformable material, a sleeve having a threaded connection with the nut of opposite hand to the screw shaft, and a yielding driving connection between the sleeve and pinion barrel including an outer barrel member fixed tothe sleeve and a ring of elastically deformable material compressed between the inner and outer barrels by longitudinal movement of the sleeve.

12. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft 'having a barrel fixed thereto, a nut threaded on the screw shaft, a yielding thrust connection between the nut and the barrel including a thrust ring of elastically deformable material, a sleeve having a threaded connection with the nut of opposite hand to the screw shaft, and a yielding driving connection between the sleeve and pinion barrel including an outer barrel member fixed to the sleeve and having a splined connection with the pinion barrel, and a ring of elastically deformable material compressed between the two barrels by longitudinal movement of the s1eeve,.said parts being so dmensioned as to permit the sleeve to run off the threads of the nut when the drive is subjected to a predetermined overload.

13. In an engine starter drive, a power shaft having a smooth portion, spline grooves adjacent thereto and a reduced smooth portion beyond the splinedportion; a pinion slidably journalled on the first smooth portion, a screw shaft engaging the splined portion, and a collar fixed in the screw shaft bearing on said reduced smooth portion, the abutment of the collar against the end of the splined portion of the power shaft defining the operative position of the screw shaft thereon, a nut lhaving a low pitch threaded connection with the screw shaft, said screw shaft having an abutment defining the operative position of the nut, a sleeve having arhigh pitch connection to the nut of opposite hand, a thrust connection between the nut and pinion, and a yieldable driving connection between the sleeve and pinion.

14. An engine starter drive as set forth in claim 13 in which the thrust connection between the nut and pinion comprises a ring of elastically deformable material adapted to yield when longitudinal movement of the pinion is obstructed.

15. An engine starter drive as set forth in claim 13 in which the pinion has a. splined connection to the sleeve, and the yielding driving 

